"heat exchanger corrosion from ammonia in reuse water"

Question:

"We are working on a project where municipal wastewater will be highly treated and used as make-up water for a number of cooling systems, mostly at power plants. The treated water may have approximately 4 to 6 mg/l ammonia. We have heard that even trace amounts of ammonia in the presence of dissolved oxygen at elevated temperatures can lead to failure of the brasses and bronzes used in heat exchangers. Do you know of any references that document accelerated corrosion and failure of brass or bronze due to ammonia in the cooling water?"

Answer:

To effectively provide references to technical articles discussing stress corrosion cracking (scc) of brasses and bronzes in ammonia containing cooling water environments would require us conducting a literature search (of our own library plus possibly outside literature), which is outside the parameters of a discussion forum. However, the short answer to your inquiry is that ppm levels of ammonia have been known to initiate scc of susceptible brasses, and your concern is well founded.

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